We propose to continue and expand our investigations of computer-summated cerebral potentials elicited in human subjects by discrete electrical stimuli delivered to the pulp of individual teeth via electrodes implanted into dentine. This research will include: an investigation of the pre-pain range of stimulus intensities and qualities of pre-pain sensations with electrical tooth pulp stimulation; a study of the relationships among intensities of electrical stimulus to tooth pulp, subjective estimates of the effects of analgesic drugs on cerebral tooth pulp evoked potentials and subjective estimates of magnitude and quality of sensations in humans.